Molecular evidence for a single clonal origin in biphenotypic concomitant chronic lymphocytic leukemia and multiple myeloma

Abstract

To establish the clonal origin of a case of concomitant B-cell chronic lymphocytic leukemia (IgMκ) and multiple myeloma (IGAλ), we analyzed the immunoglobulin (Ig) gene rearrangements in the patient's blood and bone marrow. Despite the different isotypes, pretreatment investigation of the heavy chain gene (J(H)) revealed a germline fragment and two identical rearrangements in the blood and marrow. Both κ and λ light-chain genes were rearranged in the blood, suggesting peripheral blood lymphocyte involvement in the myeloma. Analysis of the Ig genes after chemotherapy demonstrated no change in the J(H) or C(K) rearrangements; however, the λ genes were now in a germline configuration. Our results suggest that in this patient both chronic lymphocytic leukemia and myeloma originated from the same B-cell progenitor.